Stiffening shoe uppers



United States Patent 3,239,861 STIFFENING SHOE UPPERS George Olivier Langlais, Springfield, Mass., assignor to Monsanto Company, a corporation of Delaware No Drawing. Filed Nov. 13, 1962, Ser. No. 237,303 3 Claims. (Cl. 12-146) This invention relates to a process for stiffening parts of footwear and to a rigid laminated toe portion of a shoeupper.

In the manufacturing of footwear, it is often necessary to stiffen certain parts thereof such as the toe portion of the shoe upper or the portion near the heel section. This stiffening is accomplished by treating a fibrous insert or blank with a resinous material, inserting the blank in the area to be stiffened and then conforming the assembly to the shoe last. The resinous material used for stiffening can be a thermosetting resin. The art has disclosed that certain thermosetting aminoplast resins have been used successfully. However, these resins require a hardening agent such as an ammonium salt in order to cause the resin to set up as set forth in Us. 2,512,003 and US. 2,919,453. It would be desirable to avoid the use of a hardening agent particularly in the process of manufacturing the ever-increasingly popular sports footwear which process requires heat molding or vulcanizing the footwear item. It would be advantageous to have the resin set up or cure with heat alone during heat molding or vulcanizing of the sports footwear.

Therefore, it is an object of this invention to provide a process for stiffening parts of footwear.

Another object of this invention is to provide a rigid laminated toe portion prepared by the process of this invention.

Briefly, this and other objects of this invention are attained by treating a fibrous substrate with a certain thermosetting aminoplast resin, which resin can be cured or made rigid upon the application of heat alone to provide the necessary stiffness in certain portions of the footwear as well as good water resistance.

The following examples are set forth to illustrate more clearly the principle and practice of this invention to one skilled in the art. Unless otherwise noted, all percentages and all parts are on a weight basis.

Example I A 50% aqueous solution of a melamine formaldehyde resin is prepared by dissolving a powdered melamineformaldehyde resin in an aqueous medium containing 95 parts of water and 5 parts of isopropyl alcohol. The melamine-formaldehyde resin employed herein is the con densation reaction product of 3.5 mols of formaldehyde per mol of melamine.

An 8 oz. cotton duck is coated on one side thereof with the above prepared resin composition to provide a pickup of 100% resin solids based on the weight of the dry untreated cotton duck. The sample is dried at 175 F. to remove a substantial portion of the moisture present therein. The dried sample is then stitched to a shoe upper fabric. The assembled shoe upper is then conformed to a shoe last and heated at 275 F. for about 4 minutes. The resulting product is a rigid laminated shoe upper having good adhesion between the shoe stiffener and the shoe upper fabric as well as possessing water resistance.

The present invention is directed to a process for stiffening parts of footwear articles which process comprises treating a dry fibrous material with a thermosettable aminoplast resin. The treated fibrous material is then 3,239,861 Patented Mar. 15, 1966 inserted into the part of the footwear to be stiffened. The

assembled footwear is than heat molded to the shape of a shoe last. The temperature employed herein should be at least 225 F. for at least 1 minute in order to accomplish proper setting up of the resin. Higher temperatures may be employed but caution should be used to avoid scorching the footwear material. In the process of treating the fibrous material, the amount of resin solids deposited onto the fibrous material should be 20 2O0 weight percent and, preferably, 25-100 weight percent based on the weight of the dry untreated fibrous material.

The thermosetting resin employed in the practice of this invention is an aminoplast resin prepared by the cocondensation reaction of 1.5-6.0 mols of an aldehyde per mol of aminotriazine compound using an alkaline catalyst. Typical of the aminotriazine compounds which can be employed herein are melamine, ammeline, formoguanamine, N-methyl-melamine, N-phenylmelamine, methylol melamine and the like. Typical of the aldehyde compounds which can be employed herein are formaldehyde, paraformaldehyde, benzaldehyde, acetaldehyde and the like. The preferred aminoplast resin to be employed in the practice of this invention is a melamine formaldehyde resin.

In the application of the aminoplast resin, the resin is first dissolved in an aqueous medium generally to prepare a 50 weight percent solution of the aminoplast resin in water. Sometimes it may be helpful to employ a small amount of alcohol to aid in dissolving the aminoplast resin. In addition, it may also be convenient to use a 70 weight perecent solution of the resin. As a further aid to the process itself, it may be desirable to add an amine stabilizing agent such triethylamine or triethanolamine, which amine stabilizing agent prevents the resin solution from advancing or gelling as well as stabilizing the resin when deposited onto the fibrous material until the aminoplast resin is advanced to a thermoset condition by the application of heat.

The treating of the fibrous material with the thermosetting aminoplast resin of this invention may be either by coating or by impregnating the fibrous material, depending upon the desired stiifness or end use wanted. The resin may be sprayed on the fibrous material to coat it or the fibrous material may be dipped through the resin solution to impregnate the material. In some applications it may be also desirous to coat only one side of the fibrous material particularly where the uncoated side thereof will be in actual contact with the foot of the individual wearing the footwear article.

The fibrous material employed in the practice of this invention can be any woven or unwoven fibrous material of the type generally employed by the shoe industry in preparing stiffening blanks or inserts and include knitted or felted textile materials.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are effectively attained and since certain changes may be made in the above composition as set forth without departing from the scope of this invention, it is intended that all matters contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A process for stiffening parts of footwear articles which process comprises treating a dry fibrous material with a thermosettable melamine-formaldehyde resin so that the fibrous material has deposited thereon 20-20O weight percent of the resin solids based on the weight of the dry untreated fibrous material, inserting the treated fibrous material into the portion of the footwear to be stiffened and heat molding the assembled footwear to the shape of the last at a temperature of at least 225 F. for

at least 1 minute; said thermosettable resin being the cocondensation reaction product of 1.56.0 mols. of formaldehyde per mol of melamine.

2. The process of claim 1 wherein the fibrous material is treated with 25-100 weight percent of the resin solids of the thermosettable aminoplast resin.

3. The process of claim 1 wherein only one side of the fibrous material is treated with the thermosettable aminoplast resin.

References Cited by the Examiner UNITED STATES PATENTS 2,512,003 6/1950 Wedger 12146 2,919,453 1/ 1960 Shuttleworth l2-146 2,935,753 5/1960 Heaton 12-146 2,958,880 11/1960 Morse 12146 FRANK I. COHEN, Primary Examiner. 

1. A PROCESS FOR STIFFENING PARTS OF FOOTWEAR ARTICLES WHICH PROCESS COMPRISES TREATING A DRY FIBROUS MATERIAL WITH A THERMOSETTABLE MELAMINE-FORMALDEHYDE RESIN SO THAT THE FIBROUS MATERIAL HAS DEPOSITED THEREON 20-200 WEIGHT PERCENT OF THE RESIN SOLIDS BASED ON THE WEIGHT OF THE DRY UNTREATED FIBROUS MATERIAL, INSERTING THE TREATED FIBROUS MATERIAL INTO THE PORTION OF THE FOOTWEAR TO BE STIFFENED AND HEAT MOLDING THE ASSEMBLED FOOTWEAR TO THE SHAPE OF THE LAST AT A TEMPERATURE OF AT LEAST 225*F. FOR AT LEAST 1 MINUTE, SAID THERMOSETTABLE RESIN BEING THE COCONDENSATION REACTION PRODUCT OF 1.5-6.0 MOLS OF FORMALDEHYDE PER MOL OF MELAMINE. 